In offshore production well systems it is desirable to be able to quickly and effectively reconnect a riser from an overhead vessel to a casing in a subsea wellhead. One of the primary problems which must be overcome in so doing, however, is the difficulty in creating an effective seal between the riser and the casing. One of the seals that has been utilized in subsea connections is a metal-to-metal type seal.
The metal-to-metal type seal, to be effective, requires that a high compressive force be placed on it. The mechanisms previously used in connection with the metal-to-metal seal have been complicated and cumbersome and have not provided the desired degree of sealing between the riser and the subsea casing. As a result, the remote latching and sealing of the tieback string to the wellhead has gone neither as smoothly, nor as quickly, as desired.
Accordingly, it is the principal object of the present invention to remotely latch and seal a tieback string to a production wellhead.
Another object of this invention is to remotely latch and seal a tieback string to a production wellhead quickly and efficiently.
A further object of this invention is to apply compressive force to a metal-to-metal type seal with an uncomplicated mechanical arrangement.